I fold my fabric selvage to selvage adjusting it left to right to get the grain as straight as possible, then fold in half again bringing the lengthwise fold down to the selvage, roll the length around an omnigrid ruler, pull the ruler out then stack my fabrics by color on shelves. Folding the fabric this way allows me to roll out a portion of the fabric and rotary cut off the amount I need with as little handling of the fabric as possible.

I fold mine in half and then wrap it around an 8 1/2" x 24" ruler. It would also work with the 6" x 24" ruler.

This is what I do too, fold the fabric selevedge selevedge and then roll it over my 6.5x24 ruler. This way all fabrics will have the same width, height depends on how much yardage. When I stack them by colors and put them in my clear drawer storage cabinets with the fold showing, they look so neat and it is easy to see without opening the drawer, and I can also estimate how much fabric I have based on the thickness without getting out...love this system.